Fluorenone and 2-vinylfluorene are known compounds. However, the oxidation of 2-vinylfluorene to 2-vinylfluorenone is problematical due to the reaction of the vinyl group during oxidation. In order to convert 2-vinylfluorene to 2-vinylfluorenone it is necessary to employ an oxidant which is sufficiently strong to cause the desired oxidation without causing prepolymerization or other undesirable side reactions.
Preparation of 2-vinylfluorenone would be desirable since it can be polymerized to provide poly-2-vinylfluorenone. This polymer is of interest since it has been found to be an excellent insulator which can be applied to conductive substrates from solution. The monomers themselves possess this insulating property; however, it is preferred to polymerize the monomer before its application to the substrate or to cause polymerization in situ after such application due to the enhanced mechanical properties of the polymer film as compared to a film of the monomer. However, the inability of the prior art to come up with a method to prepare 2-vinylfluorenone has hindered attempts to prepare the polymer. An alternate route for preparation of the polymer, i.e. preparation of poly-2-vinylfluorene with subsequent oxidation of the fluorene units to fluorenone, has not been entirely successful. For example, it is reported in Polymer Letters, Vol. 9, pp. 671-676 (1971) that a 50/50 copolymer of 2-vinylfluorene/2-vinylfluorenone can be prepared by the oxidation of poly-2-vinylfluorene with chromium trioxide in glacial acetic acid. This reference illustrates the difficulty of obtaining complete oxidation by pointing out that a residue having an oxygen analysis indicating almost complete conversion to poly-2-vinylfluorenone was insoluble in organic solvents and strong acids. This insolubility, which is probably due to extensive crosslinking during the oxidation, is undesirable since the polymers cannot be applied to substrates from their solutions in organic solvents. It appears, from the state of the art, that the only way to prepare poly-2-vinylfluorenone containing no fluorene units in a form which is soluble in common organic solvents is to prepare 2-vinylfluorenone and cause its polymerization.
Accordingly, it would be desirable and it is an object of the present invention to provide a method for the preparation of 2-vinylfluorenone.
An additional object is to provide, as a composition of matter, 2-vinylfluorenone, .alpha.-methyl-2-vinylfluorenone and substituted derivatives thereof.
An additional object is to provide polymers of 2-vinylfluorenone and .alpha.-methyl-2-vinylfluorenone.
A further object is to provide copolymers of 2-vinylfluorenone with other vinyl monomers.